Quinacridones are well known organic pigments. They may be manufactured by acid catalyzed ring closure of aniline-terephthalic acids. The color and other properties of quinacridone pigments are determined by their substitution and crystal structure. Another well known form that affects color and other properties is the forming of solid solutions. One such quinacridone solid solution is formed from the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone, which is known as Color Index Pigment Violet 55. Examples of solid solutions formed from different ratios of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone are shown in U.S. Pat. No. 5,236,498.
Impurities produced during the synthesis of quinacridones also affect the properties of the final pigment and reduce the amount of pigment produced.
Consequently, a need exists for new quinacridone pigments that have an extended range of colors that can be produced with a minimum of impurities and have the desired chroma, hue, bleed resistance and durability.